Do people usually use just plain LEDs or get the ones with the "socket" attached so that they just plug in?

Also, if people use the socket style, what about the ones behind the heat/cooling? Are those sockets?

I just want to plan ahead so that I can spend just one day ripping things apart and putting it back together instead of ripping it apart, finding out what I need, put it back together, get the LEDs, rip it all apart again, and install everything...

Thanks for any tips.